Chapter 3. NFS and the User-De®ned File System (UDFS)

A user-de®ned ®le system (UDFS) is a type of ®le system that you directly manage

through the end user interface. This contrasts with a system-de®ned ®le system

(SDFS), which AS/400 system code creates. QDLS, QSYS.LIB, and QOPT are all

examples of SDFSs.

The UDFS introduces a concept on AS/400 that allows you to create and manage

your own ®le systems on a particular user Auxiliary Storage Pool (ASP). An ASP is

a storage unit that is de®ned from the disk units or disk unit sub-systems that make

up auxiliary storage. ASPs provide a means for placing certain objects on speci®c

disk units to prevent the loss of data due to disk media failures on other disk units.

 

The concept of Block Special Files (*BLKSF objects) allows a user to view a UDFS

 

as a single entity whose contents become visible only after mounting the UDFS in

 

the local namespace. An unmounted UDFS appears as a single, opaque entity to

 

the user. Access to individual objects within a UDFS from the integrated ®le system

 

interface is permissible only when the UDFS is mounted.

UDFS support enables you to choose which ASP will contain the ®le system, as

well as manage ®le system attributes like case-sensitivity. You can export a

mounted UDFS to NFS clients so that these clients can also share the data that is

stored on your ASP. This chapter explains how to create and work with a UDFS so

that it can be used through NFS.

 

 

 

 

User File System Management

 

The UDFS provides new ®le management strategies to the user and includes

 

several new and changed CL commands speci®c to UDFSs.

 

For more information about the various UDFS CL commands and their associated

 

parameters and options, see CL Reference, SC41-4722.

 

Create a User-De®ned File System

 

The Create User-De®ned File System (CRTUDFS) command creates a ®le system

 

whose contents can be made visible to the rest of the integrated ®le system

 

namespace via the ADDMFS (Add Mounted File System) or MOUNT command. A

 

UDFS is represented by the object type *BLKSF, or block special ®le. Users can

 

create a UDFS in an ASP of their own choice and have the ability to specify

 

case-sensitivity.

 

Restrictions:

 

1. You must have *IOSYSCFG special authority to use this command.

© Copyright IBM Corp. 1997, 1999

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IBM AS/400E manual NFS and the User-Dened File System Udfs, User File System Management, Create a User-Dened File System
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AS/400E specifications

The IBM AS/400E, now more commonly known as IBM i, is a robust and versatile midrange server that has been designed to provide a comprehensive computing solution for businesses of all sizes. First introduced in the late 1980s, the AS/400 series has undergone multiple enhancements and rebranding, with the AS/400E being one of the notable iterations. This powerful platform is closely associated with IBM's commitment to reliability, scalability, and integrated business solutions.

One of the main features of the AS/400E is its highly integrated architecture that combines hardware and software into a cohesive system. This integration allows for seamless operations, reducing the complexity typically associated with managing disparate systems. The system is powered by IBM's proprietary OS/400 operating system, which has evolved into IBM i, featuring advanced capabilities like object-oriented programming, integrated database management, and security features that are essential for enterprise environments.

A key characteristic of the AS/400E is its robust database support, primarily through the use of DB2 for i. This integrated database management system enables efficient data handling and retrieval, facilitating real-time business analytics and reporting. Furthermore, the platform supports a variety of programming languages, including RPG, COBOL, and Java, making it flexible for developers who require diverse tools for application development.

The AS/400E is also known for its exceptional reliability and uptime, making it a preferred choice for critical business applications in industries such as finance, healthcare, and manufacturing. This reliability is backed by advanced error detection and correction mechanisms, as well as redundancy features that help prevent data loss and minimize downtime.

In terms of scalability, the AS/400E can effortlessly expand to accommodate growing business demands. Organizations can increase processing power by adding more resources without significant disruption. This scalability, combined with the system’s built-in virtualization capabilities, allows businesses to optimize resource usage and streamline operations.

Security is another defining feature of the AS/400E. The platform incorporates various layers of security measures, including user authentication, encryption, and comprehensive auditing capabilities, ensuring that sensitive business data is protected against unauthorized access.

Overall, the IBM AS/400E remains a powerful tool in the enterprise computing landscape, providing businesses with an integrated, reliable, and secure solution for their technological needs. Its enduring popularity is a testament to its capability to evolve with changing business requirements while maintaining its core attributes of high performance and stability.
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